The rotor contains a permanent magnet with a north and south pole at opposite ends. The rod of the rotor is a conductive metal with a brush at one end that connects to the end of the field coil where u see the switch in the circuit. At the other end is two brushes which are represented above by the two poles of the switch. Where the brushes connect to the rod, place electric tape or other insulation on one half of the surface of the rod to create commutation. This could also instead of brushes be a literal switch like I have in the circuit above. I can't remember what it's called but I've used switches that are push switches that you can easily set up something with the rotor to where the rotor is physically hitting a surface attached to the throw to click it. Just make sure it's aligned in way with the magnet so that it's rotating the coil generating the stator field 180 degrees to the opposite pole of the rotor magnet.
